時差N小時:計(jì)劃生育 蚜蟲的風(fēng)格

If you keep a garden and have never beenbothered by aphids, you are lucky. But one day youmay find your rose bushes or bean plants covered--almost overnight--with these green, greedy sap-suckers. What allows aphids--and thousands of otherspecies--to appear so fast is a trick these insectshave developed for circumventing the old rule aboutthe birds and the bees.

如果你有個花園，卻從來沒被蚜蟲侵?jǐn)_過，那你就很幸運(yùn)了。但是你有可能發(fā)現(xiàn)園子里的玫瑰叢和豌豆葉上，幾乎一夜之間爬滿了綠幽幽，貪婪狂吃的蚜蟲。是什么讓這些蚜蟲以及其它成千上萬種蟲子如此迅速地出現(xiàn)，這是蟲子為規(guī)避鳥類和蜜蜂舊的食物鏈規(guī)則發(fā)展而來的訣竅。

During the summer months when aphid-food is plentiful, aphids reproduce through aprocess called "parthenogenesis," from the Latin words "virgin birth." What that means is thatfemale aphids give birth to more female aphids without ever seeing a male. As soon as thosedaughters mature, they produce their own offspring, and so on.

在夏季的幾個月期間，蚜蟲的食物充足，它們會通過單性生殖方式繁殖后代，"parthenogenesis"這一詞來源于拉丁語“virgin birth(圣靈感孕)”，意思就是雌性蚜蟲不與雄性交配而生出許多雌性蚜蟲。雌性蚜蟲的女兒們一成熟，就立即繁衍自己的后代，如此以往。

Without the search for mates or the ensuing courtship rituals, parthenogenesis means bigsavings in time and energy: in just one season, a single aphid can give rise to billions ofdescendants.

單性生殖不需要蚜蟲去尋找雄性配偶，更省略了隨之而來的求愛儀式，因此十分節(jié)省時間和精力：在一個季節(jié)里，一只蚜蟲會繁衍出十多億后代。

But in the fall, fresh food gets harder to find and there'd no longer be any reason forproducing so many offspring. So now a generation of aphids is born that includes males as wellas females. And what happens next between the males and females is just what you mightexpect.

但是到了秋天新鮮食物很難找，這時就沒必要去生產(chǎn)那么多子孫了。在新生一代蚜蟲里既有雌性也有雄性。你可能會想到在雌雄性蚜蟲之間接下來會發(fā)生什么。

Why aphids would turn from parthenogenesis to something as messy and inefficient as sexis another story, but in short, sexual reproduction is nature's way of shuffling the genes tocreate variety. Each of the offspring inherits a random mix of the parents' genes. Andvariety is what enables species to adapt and evolve as the environment changes.

為什么蚜蟲會從單性生殖轉(zhuǎn)為即紊亂又效率低下的有性生殖，這又是另一個故事了。簡而言之，有性生殖是自然的基因重組方式，以創(chuàng)造多樣的個體。每一個后代都遺傳了父母隨機(jī)組合的基因。多樣性則是為了物種進(jìn)化以適應(yīng)環(huán)境的變化。

But when summer returns and the living is easy, the aphids give up on variety andreproduce once again in the fastest way they know how.

但是在下一個夏季，生存又變得容易起來，蚜蟲就會放棄多樣性，以它們掌握的最快的方式重新生殖。